Federico Sirri

Over recent years the use of yeast in feedstuffs has gained momentum due to novel developments in single‐cell proteins (SCPs). SCPs are considered a sustainable protein source, as their production enable to convert low‐value substrates (including industrial/agricultural wastes) into feed, with a related reduced environmental impact. This study provides a first‐step insight into the dietary inclusion of torula yeast‐derived SCPs in broiler chicken diets. A total of 720 1‐day‐old male broilers were divided into four groups (10 replicate pens/group): the control group (CON) received a commercial soybean‐based diet, while the SCP groups (SCP2, SCP4, SCP6) were fed diets supplemented with 2%, 4%, or 6% SCPs during the grower and finisher phases (15–42 d) as a partial replacement for soybean meal. Growth performance, footpad dermatitis (FPD), plasma metabolome, and breast‐meat quality and composition were evaluated. For the entire trial period, performance traits and FPD rates did not differ significantly, however a trend was observed for body weight and daily weight gain which tended to decrease with increasing SCP levels (3083, 3058, 2988, 2942 g/bird, and 72.1, 71.6, 69.8, 68.8 g/bird/day respectively for CON, SCP2, SCP4, and SCP6; p = 0.071; linear fit < 0.01). Breast‐meat quality and composition were maintained apart from linearly increased yellowness (b*) in CON, SCP2, SCP4, and SCP6 (7.67, 8.57, 9.11, and 10.38; p < 0.001; linear fit < 0.01). As for plasma metabolites, focusing on differences attributable to SCPs inclusion levels, on day 21, SCP6 reduced Threonine (−34%) and increased Isoleucine (+26%), Ethanol (+91%), Uridine (+67%), Leucine (+24%), and 2,3‐butanediol (+60%) compared with CON ( p < 0.05). At day 42, SCP6 reduced Arginine (−46%) and Threonine (−17%) and increased 2‐aminobutyrate (+51%), Uridine (+116%), Trans‐4‐hydroxy‐L‐proline (+29%), and Formate (+25%) ( p ≤ 0.05). Overall, the findings demonstrate the feasibility of graded SCPs inclusion in broiler diets, with a potential upper limit of 4%, as indicated by changes in performance and plasma metabolome.

A trial was conceived to evaluate the effects of the dietary inclusion of defatted BSF larvae meal on growth performance, breast meat quality traits, cecal microbiota composition and metabolomics profile of turkeys. A total of 1512 female turkeys (B.U.T. 6) were divided into two groups (9 replicate pens) fed either a basal diet (CON group) or CON diet with 5% BSF meal from 65 days to slaughtering (105 days; INS group). The administration of BSF meal improved final body weight (10.17 vs. 10.06 kg/bird, respectively for INS and CON; P = 0.04) as well as daily weight gain and feed conversion ratio in the rearing cycle (96.22 vs. 95.23 g/bird/day and 2.127 vs. 2.141, respectively; P = 0.03). Breast meat quality traits and cecal microbiota were only slightly affected by the treatment. The cecal concentration of tyramine was significantly lower in INS turkeys, which showed higher levels of glucose and malonate (P = 0.03). The use of BSF meal tended (0.05 < P < 0.10) to increase the cecal content of isoleucine, betaine and butyrate, and to reduce the amount of 3-phenylpropionate. Overall, the dietary inclusion of 5% BSF meal from 65 to 105 days improved the growth performances of female turkeys mainly through the modulation of the gut metabolomics profile.

This study aimed to demonstrate the efficacy of the analytical method proposed for the assessment of the amount of European Union (EU)-regulated perfluoroalkyl substances (PFAS) in broiler chicken livers and to perform preliminary monitoring of hepatic contamination in chickens raised in Italy under different rearing systems. A total of 21 liver samples were analyzed, revealing widespread PFAS contamination, with perfluorooctanoic acid detected in all samples at 0.48-0.66 μg/kg. Perfluorononanoic acid and perfluorohexane sulfonic acid were also found, while perfluorooctanesulfonic acid contamination was observed only in specific samples. The total PFAS amount varied across groups, even though none of the samples exceeded the EU regulatory limits. The PFAS content in livers from rural free-range chickens tended to be higher than that of their indoor counterparts (upper bound: 0.83 vs. 0.67 μg/kg; lower bound: 0.87 vs. 0.71 μg/kg, respectively; p=0.08 and p=0.06), suggesting that access to outdoor environments is a key factor involved in PFAS contamination. Further monitoring across more diverse samples is needed to confirm these preliminary findings and define mitigation strategies to reduce the risk of PFAS contamination.

This research aimed to investigate, through a multifactorial approach, the relationship among some in-vivo parameters (i.e., behavior and blood traits) in broilers exposed to chronic HS, and their implications on proximate composition, technological properties, and oxidative stability of breast meat. A total of 300 Ross 308 male chickens were exposed, from 35 to 41 days of age, to either thermoneutral conditions (TNT group: 20°C; six replicates of 25 birds/each) or elevated ambient temperature (HS group: 24 h/d at 30°C; six replicates of 25 birds/each). In order to deal with thermal stress, HS chickens firstly varied the frequency of some behaviors that are normally expressed also in physiological conditions (i.e., increasing “drinking” and decreasing “feeding”) and then exhibited a behavioral pattern finalized at dissipating heat, primarily represented by “roosting,” “panting” and “elevating wings.” Such modifications become evident when the temperature reached 25°C, while the behavioral frequencies tended to stabilize at 27°C with no further substantial changes over the 6 days of thermal challenge. The multifactorial approach highlighted that these behavioral changes were associated with oxidative and inflammatory status as indicated by lower blood γ-tocopherol and higher carbonyls level (0.38 vs. 0.18 nmol/mL, and 2.39 vs. 7.19 nmol/mg proteins, respectively for TNT and HS; p < 0.001). HS affected breast meat quality by reducing the moisture:protein ratio (3.17 vs. 3.01, respectively for TNT and HS; p < 0.05) as well as the muscular acidification (ultimate pH = 5.81 vs. 6.00, respectively; p < 0.01), resulting in meat with higher holding capacity and tenderness. HS conditions reduced thiobarbituric acid reactive substances (TBARS) concentration in the breast meat while increased protein oxidation. Overall results evidenced a dynamic response of broiler chickens to HS exposure that induced behavioral and physiological modifications strictly linked to alterations of blood parameters and meat quality characteristics.

In recent years, insect meal has attracted increasing interest as an innovative protein source to replace fish meal in feed formulation due to its valuable nutritional profile. This research aimed to compare the effects of different dietary inclusion levels (5, 10, and 15%) of Hermetia illucens (HI) larvae meal on Sparus aurata (initial weight: 98.6 ± 0.6 g) sensorial, technological, and nutritional fillets quality. Fish were fed experimental diets over 113 days. Results showed that the inclusion of defatted HI larvae meal did not induce off-flavours in gilthead sea bream fillets. No significant differences were found in appearance, mouthfeels, and texture, while a difference emerged in the trait ‘cooked chicken breast’ for odour and flavour characteristics. Moreover, fillets’ quality traits and proximate composition analyses performed did not show significant differences between the treatments. The fillets’ fatty acid content showed that higher inclusion of HI meal leads to higher saturated fatty acids content, while no significant difference in polyunsaturated fatty acids was observed among treatments. Results have a positive implication as dietary HI did not negatively affect the fatty acids composition or quality of sea bream fillets.

Little attention has been paid to the biological role of arginine and its dietary supplementation in broilers under heat stress (HS) conditions. Therefore, the main aim of this study was to assess the response of broilers to arginine supplementation and cyclic HS, with a focus on liver, pectoral muscle, and blood metabolic profiles and the cecal microbiota. Day-old male Ross 308 broilers (n = 240) were placed in 2 rooms with 12 pens each for a 44-day trial. Pens were assigned to one of two groups (6 pens/group/room): the control group (CON) was given a basal diet in mash form and the treated group (ARG) was fed CON diet supplemented with crystalline L-arginine. The total arginine:lysine ratio of CON diet ranged between 1.02 and 1.07, while that of ARG diet was 1.20. One room was constantly kept at thermoneutral (TN) conditions, while the birds in the other room were kept at TN conditions until D34 and subjected to cyclic HS from D35 onwards (∼34°C; 9:00 A.M.–6:00 P.M.). Blood, liver, Pectoralis major muscle, and cecal content were taken from 2 birds per pen (12 birds/group/room) for metabolomics and microbiota analysis. Growth performance data were also collected on a pen basis. Arginine supplementation failed to reduce the adverse effects of HS on growth performance. Supplemented birds showed increased levels of arginine and creatine in plasma, liver, and P. major and methionine in liver, and reduced levels of glutamine in plasma, liver, and P. major. HS altered bioenergetic processes (increased levels of AMP and reduced levels of fumarate, succinate, and UDP), protein metabolism (increased protein breakdown to supply the liver with amino acids for energy production), and promoted the accumulation of antioxidant and protective molecules (histidine-containing dipeptides, beta-alanine, and choline), especially in P. major. Arginine supplementation may have partially counterbalanced the effects of HS on energy homeostasis by increasing creatine levels and attenuating the increase in AMP levels, particularly in P. major. It also significantly reduced cecal observed diversity, while HS increased alpha diversity indices and affected beta diversity. Results of taxonomic analysis at the phylum and family level are also provided.

Background: Arginine is an essential amino acid for chickens and feeding diets with arginine beyond the recommended levels has been shown to influence the growth performance of broiler chickens in a positive way. Nonetheless, further research is required to understand how arginine supplementation above the widely adopted dosages affects metabolism and intestinal health of broilers. Therefore, this study was designed to assess the effects of arginine supplementation (i.e., total arginine to total lysine ratio of 1.20 instead of 1.06–1.08 recommended by the breeding company) on growth performance of broiler chickens and to explore its impacts on the hepatic and blood metabolic profiles, as well as on the intestinal microbiota. For this purpose, 630 one-day-old male Ross 308 broiler chicks were assigned to 2 treatments (7 replicates each) fed a control diet or a crystallineL-arginine-supplemented diet for 49 d.Results: Compared to control birds, those supplemented with arginine performed significantly better exhibiting greater final body weight at D49 (3778 vs. 3937 g;P < 0.001), higher growth rate (76.15 vs. 79.46 g of body weight gained daily;P < 0.001), and lower cumulative feed conversion ratio (1.808 vs. 1.732;P < 0.05). Plasma concentrations of arginine, betaine, histidine, and creatine were greater in supplemented birds than in their control counterparts, as were those of creatine, leucine and other essential amino acids at the hepatic level. In contrast, leucine concentration was lower in the caecal content of supplemented birds. Reduced alpha diversity and relative abundance of Firmicutes and Proteobacteria (specificallyEscherichia coli), as well as increased abundance of Bacteroidetes andLactobacillus salivariuswere found in the caecal content of supplemented birds.Conclusions: The improvement in growth performance corroborates the advantages of supplementing arginine in broiler nutrition. It can be hypothesized that the performance enhancement found in this study is associated with the increased availability of arginine, betaine, histidine, and creatine in plasma and the liver, as well as to the ability of extra dietary arginine to potentially ameliorate intestinal conditions and microbiota of supplemented birds. However, the latter promising property, along with other research questions raised by this study, deserve further investigations.